The invention relates to an uncoupling element for uncoupling vibrations in an exhaust gas conduit of an internal combustion engine, having a screw thread-shaped or annular waved, metallic corrugated hose, which is installed between a first conduit element arranged upstream and a second conduit element arranged downstream.
With exhaust gas conduits of motor vehicles, it is known to install a flexible conduit element in the form of waved, corrugated hose as an intermediate part, in order to absorb motions and vibrations and to uncouple transmission to adjacent components. Such motions and vibrations result on the part of the elastically mounted drive mechanism as a consequence of load shifting reactions in normal driving operation or also as temperature-conditioned changes in length within the exhaust gas conduit. Transmission of these motions and vibrations to the vehicle should be prevented as far as possible, in order to increase the lifetime of the exhaust gas facility and to prevent undesirable transmission of body noise, as well as the emission of air noise.
An example of such a flexible conduit element for exhaust gas conduits of motor vehicles may be taken from German utility model DE 296 09 293 U1. The conduit element described there is firmly connected with the conduit elements lying upstream and downstream, usually by means of a welding connection. For bracing in the axial direction, the corrugated hose is enclosed by a knit hose fastened on both ends of the corrugated hose. In the cited utility model, it is moreover proposed to additionally enclose the knit hose with a netting hose.
Such a known uncoupling element is indeed gas-tight and internally stable, but the installation of this conduit element in the exhaust gas facility by the motor vehicle manufacturer must be conducted very carefully. Fastening of the connection ends of the corrugated hose may be undertaken only within narrow tolerances. Even the replacement of a corrugated hose, which has possibly become harmful, requires exact processing by the workshop entrusted with it, as well as good capabilities in metalworking.
As an alternative to permanent installation of a conduit element just mentioned, it is known according to the prior art, for example from German published patent application DE 35 42 684 A1, to separably connect the exhaust manifold of a motor vehicle engine with a following corrugated hose. In this publication, the connection is undertaken by means of a sealing ring of slightly pre-stressed material, such as metal wires or metal shavings, which is arranged on the cylindrical running-out tube end and on which a bent collar of the corrugated hose is laid, wherein a profile clamp braces the collar together with the sealing ring on the tube end. It has become apparent though, that the uncoupling action of such a separable construction is capable of improvement. Also, a corrugated hose with good uncoupling action can hardly be joined in this manner with the tube end of a conduit element of an exhaust gas facility close to the engine.